An Investigation of Equilibrium Iron Thermochemistry in Flames

Staude, Susanne; Atakan, Burak

doi:10.2174/1874396x00903010042

Cited by 4 publications

(3 citation statements)

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“…A detailed chemical kinetic mechanism for gaseous iron-species inhibition of flames, iron pentacarbonyl (Fe(CO) 5 ) mechanism, has been introduced, and modeling with the mechanism supports the premise that the inhibition is primarily a gas-phase phenomena. Many researchers used the Fe(CO) 5 mechanism to investigate the influence of Fe(CO) 5 on combustion flames, and the mechanism was validated by experimental results. − Understanding the behaviors of promotion of CO oxidization and inhibition of NO formation by gaseous iron and iron oxides at high-temperature off-gas combustion is important for the control of CO and NO emissions. There are no reports in the literature of NO by iron-containing compounds in steelmaking off-gas combustion conditions.…”

Section: Introductionmentioning

confidence: 99%

“…Many researchers used the Fe(CO) 5 mechanism to investigate the influence of Fe(CO) 5 on combustion flames, and the mechanism was validated by experimental results. [12][13][14][15][16] Understanding the behaviors of promotion of CO oxidization and inhibition of NO formation by gaseous iron and iron oxides at high-temperature off-gas combustion is important for the control of CO and NO emissions. There are no reports in the literature of NO by ironcontaining compounds in steelmaking off-gas combustion conditions.…”

Section: Introductionmentioning

confidence: 99%

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Promotion of CO Oxidization and Inhibition of NO Formation by Gaseous Iron Species during High-Temperature Off-Gas Combustion

Wei

2011

Energy Fuels

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The promotion of CO oxidization and inhibition of NO formation by gaseous iron species were analyzed using the Sandia SENKIN program. It is shown that the relative ratio of CO oxidization dramatically varies with combustion time at early burning stage in the presence of iron species, and all peak values are greater than 2.4. The relative ratio of CO oxidization decreases with the increase of air stoichiometric ratio and CO concentration in off-gas. The circulation reactions of Fe-FeO/FeO 2 -Fe achieve the catalytic effect on CO oxidization. Gaseous iron species can greatly inhibit NO formation, NO reduction ratio can reach above 70% at T = 2073 and 2273 K, and gaseous iron species can effectively inhibit NO formation when combustion temperature is not higher than 2273 K during the off-gas combustion. There are O 2 competitive reactions between thermal NO formation and Fe oxidization, and high chemical activity of iron species inhibits thermal-NO formation. INTRODUCTIONA large amount of high-temperature off-gas is produced during oxygen converter steelmaking, the major compositions of off-gas are CO and CO 2 , CO concentration varies from 15 to 70%, and off-gas temperature can reach 1900 K. 1 In the meantime, off-gas entrains a large amount of fine dusts (Fe, FeO, Fe 2 O 3 , etc.) and the amount of the dusts entrained by off-gas is about 80-150 g/m 3 . 2 The high-temperature off-gas is a precious valuable fuel. It is often discharged into the cooling stack to be combusted, and the peak temperature of flame can reach above 2000°C where CO 2 may decompose and NO x is significantly formed. 3 CO emission concentration can reach above 2000 mg/m 3 which is always over emission standards (300 mg/m 3 in China). 4,5 CO is a toxic gas which is dangerous to human health. High CO emission results in not only atmospheric pollutant but also fuel loss. NO x is a known precursor to the formation of ozone and acid rain, and it can react with volatile organic compounds to form photochemical smog. 6 Iron oxide catalyst is widely used either as single metal oxide or as a mixed oxide in industrial processes, and iron oxide exhibits intermediate activity in the complete oxidation of methane and carbon monoxide. 7-9 NO reduction by iron species has been studied in fluidized bed, and the results indicate that iron or its oxides cause a chemical reduction of NO in the presence of CO. 10 It has been discovered that injection of iron-containing compounds into the combustion and reburning zones of conventional gas-and coal-fired combustors can increase the efficiency of NO x reduction by up to 20% in comparison with that which can be achieved by basic reburning. 11 During the combustion of high-temperature off-gas entraining a large amount of dust containing iron and iron oxides, gaseous iron species is present at T > 2073 K, and it has effects on CO oxidization and NO formation. A detailed chemical kinetic mechanism for gaseous iron-species inhibition of flames, iron pentacarbonyl (Fe(CO) 5 ) mechanism, has been introduced, 12 and modeling ...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Promotion of CO Oxidization and Inhibition of NO Formation by Gaseous Iron Species during High-Temperature Off-Gas Combustion

Wei

2011

Energy Fuels

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“…Staude and Atakan carried out equilibrium calculations for iron-doped hydrogen/oxygen/argon and propene/oxygen/argon gas mixtures under combustion-relevant conditions. It is noteworthy that condensed Fe-containing compounds were considered in the calculations.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of Inhibition of Hydrogen/Air Flames by Atomic Iron

2010

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The inhibition of laminar premixed H 2 /air flames by atomic iron was studied for various equivalence ratios using numerical methods. The inhibition effectiveness was shown to strongly depend upon the equivalence ratio, with the minimum effectiveness being observed at φ ≈ 2. Calculations of the recombination rates of H and O atoms and OH radicals in reactions involving iron-containing species revealed the causes of the higher inhibition effectiveness in lean and near-stoichiometric (φ < 2) and rich (φ > 2) flames. The higher inhibition effectiveness in lean flames is due to the optimal composition of iron-containing combustion products, resulting in a high recombination rate of active flame species. Increased inhibition effectiveness in rich flames is due to a low rate of chain branching under fuel-rich conditions rather than a high rate of active species removal from the flame zone.

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